2 Ona New Method of recording differences of Declination. 
old methods. More than a year has elapsed since I presented to 
the American Association some three thousand observations, — 
taken in twelve nights, by the new apparatus, (a number exceed- 
ing the recorded observations of a'whole year at one of the old- — 
est European observatories,) each of these observations present- 
ing an accuracy superior to those obtained by the o . 
This astonishing rapidity and accuracy gave rise to a debate, 
and finally to the appointment of the committee above alluded 
to. A multitude of observations have been made during the 
past year, (and in accordance with the request of the chairman 
of this committee,), varied with a view to test in every way the 
powers of the new machinery. The results, as will be seen by 
examiuing the report of the committee, were entirely satisfactory. 
t is proper now to state that, by the new invention, the transit 
instrument is converted, (at trifling expense;) into a declinometer, 
or instrument for measuring N. P.D., or declination. The ob- 
server is released from the necessity of reading a divided circle, 
and the position of his instrument at the moment his star is bi- 
sected by the declination wire, is, by a single touch, engraved on 
t of any minute distances.. The instrument used thus 
far is a transit by Dollond, the property of the U. 8. Coast Sur- 
vey, and furnished by the Superintendent of that work. It is of 
old construction, about five feet focus, and although the defini- 
tion of its object-glass is satisfactory, yet the optical power 1s 
low, and a bisection by it is far inferior to one made with-a pow- 
erful object-glass. The new machinery attached to this transit, — 
to convert it into a declinometer, was made in the Observatory by _ 
my assistant and myself, and is, of course, comparatively rough. — 
The micrometer was made in this city, and although of work 
. examina- — 
tions have been confined to zones not exceeding twenty-five de- — 
grees in width. There is no difficulty however in ‘extending — 
these researches through the entire heavens 
ing on the same night the entire sweep 
